High pressure open discharge pump system

ABSTRACT

A high-pressure cam driven open discharge pump system is provided, wherein a high-pressure output at a relatively constant pressure is formed. The pump system includes a plurality of pressurizing subassemblies, each subassembly including a cam follower retained by a cam follower support guided by guide bearings to induce linear motion of a connected piston rod. The piston rod is slidably received within a removable high-pressure cylinder assembly which retains a high pressure cylinder.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A “SEQUENCE LISTING”

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to high pressure pump systems, and moreparticularly, to a cam driven high pressure open discharge pump systemproviding substantially constant pressure output with increasedefficiency, and reduced maintenance downtime.

2. DESCRIPTION OF RELATED ART

Pumps have been historically used for a variety of applicationstypically involving the transfer of liquids. The development of pumpshas provided increased availability of pumping pressures. As pumpingpressures have increased, the applications for such high pressurestreams have increased.

Reciprocating piston pumps have been used to provide elevated flow ratepressures. However, the reciprocating piston pumps generate anundesirable pulse in the output pressure. Many recently developedapplications for high-pressure systems require minimal spikes in theoutput pressure.

Centrifugal pumps are typically able to provide relatively constantoutput pressures, but cannot sufficiently produce high pressure and arerelatively inefficient.

Therefore, the need exists for a high pressure pump system which canprovide a relatively high and stable output pressure efficiently. Theneed also exists for a high pressure pump system that can providecomponent interchange, without extended downtime. The need furtherexists for a pump system that can be tailored to a specific application,without requiring complete retooling for manufacture of the system.

BRIEF SUMMARY OF THE INVENTION

The present pump system provides a substantially constant flow rate at adesired high pressure output. In addition, the pump system is capable ofdelivering high-pressure liquids such as water, water with additives,liquid nitrogen as well as vegetable oils at constant elevated pressuresand flow rates over substantial periods of operation. As used herein,the term “constant” is taken to be within 10% of a given predeterminedvalue. The constant flow high-pressure liquid supply from the presentpump system can be used for material cutting in the abrasive jet andfluid jet industries. In addition, applications which do not requirethrough cutting of material such as cleaning, surface preparation,surface removal, milling, cleaning, sterilization and etching can employa constant high-pressure liquid supply.

The present pump system includes a base plate; a cam shaft rotatablymounted to the base plate; a cam affixed to the cam shaft for rotationwith the cam shaft; at least two pressurizing subassemblies in contactwith the cam, each pressurizing subassembly including: (i) a pistonguide block connected relative to the base plate; (ii) a piston rodslidably connected to the piston guide block; (iii) a cam followersupport releasably connected to the piston rod; (iv) a cam followerconnected to the cam follower support to contact the cam; and (v) a highpressure cylinder assembly releasably connected to the guide block toreceive a length of the piston rod, the high pressure cylinder assemblyincluding at least one sealed interface between the piston rod and thehigh-pressure cylinder assembly; a linear guide bearing connecting thecam follower support to the base plate; and a tie brace connected toeach piston guide block. In a further configuration, the tie brace isrotatably connected to the camshaft, and in another construction atleast one tie brace is connected to the base plate.

Further constructions of the pump system can include a plurality ofpressurizing subassemblies, inlet and outlet check valves locatedupstream and downstream of the pump assembly, respectively; linear guidebearings connecting the cam follower support to the base plate.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a perspective view of a high pressure pump system.

FIG. 1 b is a perspective view of the high pressure pump system of FIG.1, with the tie brace removed.

FIG. 2 is an exploded perspective view of the high pressure pump systemof FIG. 1.

FIG. 3 is an exploded perspective view of a portion of the high pressurepump system.

FIG. 4 is an exploded perspective view of a portion of the high pressurepump system with the tie brace not shown.

FIG. 5 is a top plan view of the high pressure pump system, without atie brace.

FIG. 6 is a side elevational view of the high pressure pump system asshown in FIG. 5.

FIG. 7 is a perspective view of the high pressure cylinder assembly ofFIG. 1.

FIG. 8 is a side elevational view of the high-pressure cylinder assemblyof FIG. 7.

FIG. 9 as a cross-sectional view of the high pressure cylinder assemblyof FIG. 7.

FIG. 10 is a top plan view of a first configuration of a valving body.

FIG. 11 as a front end elevational view of the valving body of FIG. 10.

FIG. 12 is a rear end elevational view of the valving body of FIG. 10.

FIG. 13 is a cross-sectional view taken along lines 13-13 of FIG. 10.

FIG. 14 is a partial enlarged cross-sectional view of the valving bodyof FIG. 10 taken along lines 14-14.

FIG. 15 is a top plan view of an alternative valving body.

FIG. 16 is a front end elevational view of the valving body of FIG. 15.

FIG. 17 is a rear end elevational view of the valving body of FIG. 15.

FIG. 18 is a cross-sectional view taken along lines 18-18 of FIG. 15.

FIG. 19 is an enlarged partial cross-sectional view taken along lines19-19 of FIG. 15.

FIG. 20 is a side elevational view of a piston rod.

FIG. 21 is a top plan view of a seal.

FIG. 22 is a side elevational view of the seal of FIG. 21.

FIG. 23 is a side elevational view of an alternative seal body.

FIG. 24 is a cross sectional view of a seal assembly employing the sealbody of FIG. 23.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 and 2, a high-pressure pump system 10 includes adrive mechanism 20 and a pump assembly 40.

The drive mechanism 20 is connected to the pump assembly 40 to provide amotive force for the pump assembly. The drive mechanism 20 includes amotor 22 and a transmission gearing such as a gearbox 24. The motor 22can be one of AC or DC, with any style of electric coil or a magneticmotor such as a servo, stepper, inverter or vector motor. The motor 22can be a constant or a variable speed motor. Alternatively, the motor 22can be operated at a constant speed or a variable speed. A typical motorwill be between 10 and 150 horsepower depending upon the numberpressurizing subassemblies and desired output flow rate and pressure,with a likely range of 25 to 75 horsepower. A satisfactory motor 22 fora two pressurizing subassembly system is an inverter rated electricmotor, on the order of 25 horsepower.

The gearbox 24 provides the transmission of power from the motor 22 tothe pump assembly 40. Preferably, the gearbox 24 provides selective gearreduction between the motor 22 and the pump assembly 40, therebyincreasing the available torque to the pump assembly. The gearbox 24 canprovide incremental or continuously variable gearing. Typically, thegearbox 24 allows for increased torque from the drive mechanism 20.Although the motor 22 and the gearbox 24 are shown as separatestructures, it is contemplated the motor and the gearbox can beintegrated into a single unit. It is further understood that a specificmotor providing the necessary torque and desired speed can be employed,wherein no gear reductions are employed. However, it is believed suchmotor is substantially more expensive than a readily commerciallyavailable motor in combination with a commercially available gearbox.

The drive mechanism 20 can be specifically configured for a given pumpassembly 40, including specific output pressure requirements and flowrates, thereby providing at least a substantially constant power output.Alternatively, the drive mechanism 20 can provide a variable poweroutput, such as in response to user control or operating environmentfeedback. For example, a PLC or motion controller can be employed togenerate a constant output. Similarly, feedback from gauges can be usedto control the output of the drive mechanism 20. For example, the gaugescan relay pressure spike signals which result in a correspondingcompensation in the speed of the drive mechanism 20.

It is contemplated the drive mechanism 20 will provide a rotation rateof approximately 30 rpm to approximately 60 rpm. However, it isunderstood different rotation rates can be employed. Typically, therotation rate is selected to at least increase the useful life of thedrive mechanism 20. Rather than require the drive mechanism to operateat inefficient or relatively determined speeds, the cam 50 can beconfigured to optimize efficiency of the drive mechanism 20, as well asimprove power consumption of the pump system 10 by improving therelationship of fluid horsepower to the drive system horsepower. Forexample, the pump system 10 can be over 95% efficient in the use ofelectric consumption to create fluid horsepower. Thus, optimization ofthe pump system 10 will result in less than 5% loss of energy throughoutthe pressurization of the fluid.

The pump assembly 40 generally includes a base plate 42, a cam 50, atleast two pressurizing subassemblies 60 and a tie brace 30.

As seen in FIGS. 1, 2-5 and 6, the base plate 42 forms a rigid platformto which the remaining components are attached or connected. The baseplate 42 can be a single integral member or can be formed of a pluralityof subplates 42′ which are fixedly connected or attached. Although thebase plate 42 can be formed from a variety of materials or manufacturingmethodologies, in view of the forces generated within the system steelhas been found to be a satisfactory material.

In addition, the base plate 42 can be a substantially planar member orcan be stepped either as an integral member or through a combination ofthe subplates 42′. Similarly, the base plate 42 can be cast, machined,welded or bonded components to provide the necessary structural rigidityand strength in a planar or configured shape.

The base plate 42 includes an aperture 43 for rotatably receiving a camshaft 52. Bearings or journals 54 are affixed to the base plate 42 forproviding a rotatable interface between the cam shaft 52 and the baseplate.

The cam 50 is connected to the cam shaft 52 for rotation therewith. Inone configuration, the cam 50 is releasably connected to the cam shaft52, such as by key ways, slots, tabs, pins, detents, retaining rings(collars), shrink fitting (sweating), clamping or other releasablemeans. It is also contemplated that a permanent connection between thecam 50 and the cam shaft 52 can be employed. However, such permanentconnected does not provide for as ready interchange of components orreplacement of worn components, and is thus believed to be inferior thanthe releasable connection.

The cam 50 includes a cam profile 56 selected to provide a substantiallyconstant high-pressure output for the pump system 10. The cam profile 56can be configured to accommodate a variety of system parameters such asfluid compression, downstream liquid volume, valving delay (timing) aswell as the desired flow rate. In addition, the cam profile 56 can beconfigured to accommodate other parameters within the pump system 10which impact at least one of the pressure or flow rate variables of thesystem output including application or use parameters. The cam profile56 is a spline curve, rather than merely an offset mounting on the camshaft 52, as the spline curve can be selected to provide the desiredconstant output. Typically, the cam profile 56 more than 50% of thelength of the profile will define a rising slope, such as, for example,60%, with at least a substantial portion of the remaining profile lengthbeing decreasing slope. Thus, the rates of acceleration and decelerationof the piston rod 90 can be controlled. It is also contemplated that byemploying at least three pressurizing subassemblies 60, a standardeccentric offset cam can be used in conjunction with a varying speed ofthe drive mechanism 20 to provide a constant output of the pump system10.

Similarly, system lag such as electrical, mechanical or fluidic lag canbe compensated by the cam profile 56. Partial or complete compensationcan be designed into the cam profile 56 or partially designed into thecam profile in cooperation with a variable speed from the drivemechanism 20. This compensation scheme can also be used to accommodatean amount of high-pressure liquid accumulation downstream of the pumpassembly 40, such as within high-pressure tubing or hoses, valves andfittings and attenuators. Typically, the amount of downstreamhigh-pressure liquid is system dependent. Different cutting systems andoperating pressures typically have different high pressure volumes.However, the downstream high-pressure volume is typically constant oncethe pump system 10 is installed. Therefore, the cam 50 and the drivemechanism 20 can be selected to provide an operating range of flow ratesand pressure.

The cam 50 is preferably formed of a relatively hard material, at leastharder than a cam follower. A satisfactory hardness is believed to beapproximately 55 to 60 on the Rockwell C hardness scale.

Also referring to FIGS. 1, 2, 5 and 6, the pressurizing subassemblies 60are located to contact the cam 50. At least two pressurizingsubassemblies 60 are employed. However, it is understood that 3, 4, 5, 6or more pressurizing subassemblies 60 can be driven by a given cam 50.

Generally, the pressurizing subassemblies 60 are located at equallyspaced locations about the cam 50. For example, 360/(number ofpressurizing subassemblies)=angle between the subassemblies.

For purposes of description, a single pressurizing subassembly 60 isdescribed in detail, with the understanding that the remainingpressurizing subassemblies are of substantially identical construction.However, it is understood different pressurizing subassemblies can beused in conjunction with a single cam 50, or individual correspondingcams on the cam shaft 52.

The pressurizing subassembly 60 includes a cam follower support 70, apiston rod 90, a piston guide block 80 and a high-pressure cylinderassembly 100.

As seen in FIGS. 1, 2, 5 and 6, the piston guide block 80 is fixedlymounted to the base plate 42. As seen in these figures, the piston guideblock 80 is fixedly connected to a subplate 42′ which in turn is fixedlyconnected to the base plate 42, thereby effectively being fixedlyconnected to the base plate. The piston guide block 80 includes anaperture 81 therethrough sized to receive the piston rod 90. Inaddition, the piston guide block 80 includes a mounting face 82 forcooperatively engaging the high pressure cylinder assembly 100.

The cam follower support 70 locates a cam follower 74 relative to thecam 50. The cam follower support 70 is slidably connected to the baseplate 42 by guide bearings 72 and preferably linear guide bearings. Theguide bearings 72 are selected to permit single axis travel of the camfollower support 70 relative to the base plate 42 and hence piston guideblock 80. The guide bearings 72 can be configured as linear bushings,slides, contact rails or grooves or other methods of providing linearmovement which dictate motion of the cam follower support 70 along asingle axis.

The cam follower support 70 can be any of a variety of configurations,such as a studded cam follower mounted to a plate or a yoke as seen inthe figures. The yoke configuration of the cam follower support 70 hasbeen found satisfactory in providing stability of the cam follower 74.Although the cam follower support 70 is shown as locating the camfollower 74 between the arms of the yoke, it is understood the yoke canbe configured as the studded cam follower mounted on a plate, which inturn is mounted to the guide bearings 72. It is also contemplated thecam 50 can have a cam profile 56 in the form of a gear (along the splineprofile) and the cam follower 74 can include a corresponding surface forengaging the spline profile gear of the cam 50 throughout rotation ofthe cam.

The cam follower 74 is connected to the cam follower support 70 forcontacting the cam 50. In one configuration, the cam follower 74 is awheel rotatably mounted to the cam follower support 70, so as to reducenonaxial forces on the cam follower support. The cam follower 74 is asofter material than the cam 50. For a cam 50 having a hardness ofapproximately 55-60 Rockwell C Hardness Scale, the cam follower 74 has ahardness of approximately 40 to 45. Thus, the cam follower 74 being astandard shape can be readily replaced, thereby increasing the usefullife of the cam 50.

The piston rod 90 is releasably connected to the cam follower support 70and is sized to be slidably received through the piston guide block 80.The piston rod 90 can be connected to the cam follower support 70 bythreaded connection collar or clamp fitting. Alternative connectionsinclude a taper lock bushing, a shrink fit collar or removable collar.The piston rod 90 can be constructed as a cylindrical smooth surfacedplunger, as shown in the figures, or a piston having a retaining groovefor retaining a sealing ring. The piston rod 90 can thus be disassembledfrom either end of the guide block 80 depending on the removal of thecollar and the relation of the guide block to the base plate 42.

Referring to FIGS. 7-9, the high-pressure cylinder assembly 100 isreleasably connected to the piston guide block 80 to receive a portionof the piston rod 90 through a range of reciprocated motion of thepiston rod. The releasable connection of the high pressure cylinderassembly 100 to the piston guide block 80 can be accomplished by any ofa variety of mechanisms, such as threaded fasteners, friction orclamping.

In one configuration, the piston 90 rod is slidably received within thehigh-pressure cylinder assembly 100, wherein the cylinder assembly doesnot include any structure for capturing or locking the piston rod withinthe high-pressure cylinder assembly. Thus, the high-pressure cylinderassembly 100 can be disconnected from the piston guide block 80 andwithdrawn from operable engagement with the piston rod 90, withoutrequiring secondary operations or disconnects.

Referring to FIG. 1 b, a return bias mechanism 95 is operably connectedbetween the cam follower supports 70, or the cam follower supports andthe base plate 42. The return bias mechanism urges the cam follower 74to remain in operable contact with the cam 50 throughout the cycle ofmotion of the piston rod 90. Thus, the complete range of motion of thepiston along both axial directions of travel is dictated by the cam 50.In one configuration, the return bias mechanism 95 includes a springurging two cam follower supports 70 together. That is, the cam follower74 connected to each cam follower support 70 is biased against the cam50, such that cam profile 56 dictates the axial velocity of the pistonrod 90.

The high-pressure cylinder assembly 100 can be a substantially integralconstruction or an assembly of individual components which can bereadily disassembled by the operator.

The high-pressure cylinder assembly 100 includes a high-pressurecylinder 110 and a valving body 120. The high-pressure cylinder 110slidably receives a portion of the piston rod 90. A sealed interface isa formed between an inner diameter of the high-pressure cylinder 110 andan outer diameter of the piston rod 90. The sealed interface is formedby a seal 116 as shown in FIGS. 21 and 22. However, alternative sealconstructions can be employed, such as a piston ring on the piston rod90, wherein the piston ring forms a sealed interface between the pistonrod and the high pressure cylinder 100.

Alternatively, the seal 116 is disposed in the annular space between thepiston rod 90 and an inner surface of the high pressure cylinder 110. Asseen in FIG. 9, the seal 116 is axially located adjacent a bushing andretained in the intended location by an axially extending cylindricalspacer 118. The spacer 118 can be sized to also contact the seal betweenthe valving body 120 and the high-pressure cylinder 110. The spacer 118is sized to substantially preclude bearing contact with the piston rod90 or the high-pressure cylinder 110. Thus, wearing forces on the spacer118 are minimized.

Referring to FIGS. 23 and 24, a further alternative seal construction isshown. In FIG. 23, a plastic seal body is shown, wherein the seal bodycan be employed in conjunction with an O-ring and a metal hoop. As seenin FIG. 24 an O-ring is installed in a grooved area of the plastic sealbody of FIG. 23, with the metal hoop also installed.

As the high-pressure cylinder assembly 100 can be readily removed fromthe piston guide block 80 and the piston rod 90 withdrawn from thehigh-pressure cylinder 110 without requiring any disconnects of the cam50, the drive mechanism 20, the cam shaft 52, the cam follower support70 or the piston rod, the seal 116 is readily accessible, and hencereplaceable. That is, the releasable connection of the piston rod 90 tothe cam follower support 70 and the high pressure cylinder assembly 100allows the seals to be readily replaced without requiring disassembly ofindividual components of the system 10.

The construction of the high-pressure cylinder assembly 100 as anassembly of separate components includes a mating plate 130, a captureplate 140, the high-pressure cylinder 110, and the valving body 120 isalso contemplated.

The mating plate 130 is selected to cooperatively, and releasably engagethe piston guide block 80. The mating plate 130 can also include a seat132 for receiving an end of the high-pressure cylinder 110. The matingplate 130 includes a central aperture 133 sized to receive the pistonrod 90. In one configuration, the central aperture 133 is sized toreceive a bushing 134 which in turn receives the piston rod 90. Themating plate 130 can be operably connected to the piston guide block 80by any of a variety of fastener such as threads, clamps, detents, stopcollars and other methods of connection. As seen in FIGS. 8 and 9, themating plate 130 includes fastening apertures 135 to receive threadedfasteners 136 which engage the piston guide block 80 to retain themating plate 130 (and cartridge 100) relative to the piston guide block.

The capture plate 140 includes a central aperture 141 sized to engage aportion of the valving body 120. The capture plate 140 is generallyspaced from the mating plate 130 by the length of the high-pressurecylinder 110 and a portion of the valving body 120. The capture plate140 thereby retains the high-pressure cylinder 110 and a portion of thevalving body 120 intermediate the capture plate and the mating plate130. A plurality of tie rods 146 can be used to pass through or engagethe capture plate 140 and correspondingly engage the mating plate 130 soas to effectively clamp or hold the high-pressure cylinder 110 and aportion of the valving body 120 between the capture plate and the matingplate. In one construction, the tie rods 146 are selected for releasableconnection so that the individual components can be replaced asnecessary or desired while maintaining a connection of the mating plate130 to the piston guide block 80. Alternatively threaded cylinder withmating threaded receptacles in the capture and mating plates arecontemplated.

The valving body 120 includes a button 122 sized to be received withinthe high-pressure cylinder 110. A sealed interface is formed between anouter diameter of the button 122 and an inner diameter of thehigh-pressure cylinder 110. An O-ring seal 126 is disposed in theannular space between the button 122 and the high pressure cylinder 110.The spacer 118 can be used to axially retain the seal 126 in the plungerstyle piston rod, but is not used in the piston ring seal style.Alternatively threaded valving body with mating threaded receptacles arecontemplated.

As seen in FIGS. 9, 10 and 13, the valving body 120 also includes ashoulder 124 sized to contact a portion of the capture plate 140 so asto retain the button 122 within the high-pressure cylinder 110.

The valving body 120 shown in FIGS. 10-14 is constructed for a pumpsystem 10 having an inlet and outlet check valve (not shown) locatedexternal to the high-pressure cylinder assembly 100. That is, thevalving body 120 has a separate inlet port and a separate outlet port,thereby providing that the low pressure incoming fluid and the highpressure outgoing fluid do not pass through the same passage in thevalving body. In this construction, the check valves can be locatedoutside of the high-pressure cylinder, and thus can be readily replacedas necessary. The inlet check valve permits the selective passage of lowpressure liquid into the pump system 10, while precluding flow in areverse direction. The outlet check valve permits the passage ofhigh-pressure liquid from the pump system 10, while precluding flow in areverse direction. Satisfactory inlet and outlet check valves have beenfound to include commercially available ball and seat style valves orpoppet style valves.

Alternatively, as seen in FIGS. 15-18, the valving body 120 can includea single passageway. In this construction, the inlet and outlet checkvalves can be located outside the pump system 10. Alternatively, theinlet and outlet check valves can be located within the high-pressurecylinder assembly 100. It is further contemplated that one of the inletor outlet valves can be inside the high-pressure cylinder assembly 100and the remaining check valve can be external to the high-pressurecylinder assembly.

The tie brace 30 is rigidly connected to at least one of the pistonguide blocks 80. The tie brace 30 can also be connected to the cam shaft52 (via the bearings 54). The bearings 54 allow rotation of the camshaft 52 relative to the tie plate 30. In such configuration, the tiebrace 30 fixes the position of the cam shaft 52 axis and the pistonguide blocks 80, thereby at least reducing relative movement of thepiston guide blocks relative to each other and the base 42. By fixingthe relative positions and orientations of the piston guide blocks 80and the cam shaft 52, the power from the drive mechanism 20 isefficiently applied to the piston rod 90 and hence the fluid. The tiebrace 30 is a rigid material such as metal or laminate. A satisfactorymaterial has been found to be steel.

It is also contemplated the tie brace 30 can be separate pieces, eachpiece connecting one guide block 80 to the base plate 42. Alternatively,the tie brace 30 can connect the guide blocks 80 together. Thus, the tiebrace 30 can connect the guide blocks 80 together, connect the guideblocks to the base plate 42 or connect the guide blocks together and theguide blocks to the base plate. The tie brace 30 can have any of avariety of configurations, including but not limited to plates, trusses,bars or brackets. It is also contemplated the tie brace 30 and the baseplate 42 can be connected together to form a frame to which the pistonguide blocks 80 are attached. The tie brace 30 reduces movement of therespective guide block 80 relative to the base plate 42, therebyreducing wear on the sealing and bearing surfaces of the pump assembly10. In addition, as the tie brace 30 reduces movement of the guideblocks 80 relative to the base plate 42, mechanical lag of the pumpsystem 10 is reduced, and thus such lag does not require compensation bythe cam profile 56.

Although not shown, a separate cam shaft support can be rotatablyconnected to the cam shaft 52 and the base plate 42 to reduce deflectionof the cam shaft under load. For example, an axial bearing can beconnected to the base plate 42, rather than the tie brace 30, so thatthe axial bearing absorbs radial forces on the cam shaft 52 and reducesdeflection of the cam shaft without requiring connection of the camshaft to the tie brace 30. It is also contemplated that the cam shaft 52can be sized to have a sufficient diameter to substantially precludeflexing under load, thereby allowing operation of the pump system 10without connection to the tie brace 30.

In an alternative construction, the piston guide blocks 80 can beconstructed to provide a bearing surface that extends along asubstantial length of the respective piston rod 90. For example, thepiston guide block 80 can have a bearing surface extending along atleast 50% of the length of the piston rod 90. In one construction, theaxial length of the bearing surface between the piston guide block 80and the piston rod 90 can be greater than the height of the piston rodfrom the base plate 42. It is also contemplated the height of the pistonrod 90 from the base plate 42 can be reduced, thereby reducing theeffective lever arm between the bearing surface of the piston guideblock 80 and the base plate 42. In one such implementation, the baseplate 42 can be constructed of differing elevations, with a reducedelevation to bring the cam 50 (and aligned subassemblies) relativelyclose to base plate 30, and a relatively elevated portion at the pistonguide blocks 80 to reduce the distance from the base plate to thebearing surface of the piston guide block.

Thus, depending upon the desired output pressure of the pump system 10,the extended bearing surface length of the piston guide block 80, thereduced lever arm distance (by individual component sizing orconstruction of the base plate 42) or a combination of both cansufficiently reduce flexing to allow operation of the pump system 10without a tie brace 30.

The pump system 10 can include downstream flow passageways forconducting the high-pressure liquid to a discharge. In oneconfiguration, the downstream flow passageways are constructed to reduceturbulence in the flow. It is believed the turbulence can be decreasedby reducing the diameter of the flow path down stream of the outletcheck valves. The reduction in the flow path diameter can beaccomplished by funneling or stepdowns. It is believed this reduction inturbulence is desirable in certain material removal applications.

Typically, the pump system 10 is used in conjunction with a downstreamsystem head not shown for expressing the high-pressure flow. The systemhead is fluidly connected to the pump system 10 by the high-pressureflow path which can include tubing, fittings, valves or other flowcontrol devices. The system head can be any of a variety ofconfigurations including an orifice, a nozzle, a focusing tube or anycombination thereof. Thus, the pump system 10 is used in an open system,wherein the high-pressure flow is expressed to a lower pressure,typically an ambient pressure.

The system head can also include forming high-pressure discharge streamsfor cutting through very soft to very hard materials. The system headcan include slitting or crosscutting in a single axis to a three axissystem, or shape profiling in two axes to seven axes with gantry orarticulated arm applications. The system head can also be handheld formanual operation or attached to robotic ambulatory devices.

It is also contemplated the downstream flow path can include anaccumulator not shown for the high-pressure liquid. Depending uponwhether an accumulator is employed in the downstream flow path, the camprofile can be constructed to accommodate the presence or absence of theaccumulator.

A controller can be operably connected to at least one of the drivemechanism 20, the pump assembly 40 and any associated monitoring devicessuch as meters or gauges. The monitoring devices can include pressuregauges located to provide a signal corresponding to a pressure in theselected portion of the pump system, temperature sensors, timing devicesas well as flow meters. Depending upon the configuration of the pumpingsystem 10, the controller can be a separate processor such as a laptopcomputer running dedicated software. Alternatively, the controller canbe integrated into the pump system, such as with the drive mechanism orthe pump assembly.

Although the pump system 10 is described in terms of a single cam 50 fora plurality of pressurizing subassemblies 60, it is contemplated thateach subassembly 60, or group of subassemblies can be driven by acorresponding cam 50. Thus, each pressurizing subassembly 60 can bedriven by a unique cam 50 (and can profile 56). For example, if fourpressurizing subassemblies 60 are to be driven, a first cam 50 on thecam shaft 52 is aligned with the first and second subassemblies, and asecond cam 50 on the cam shaft 52 is aligned with the third and fourthsubassemblies. Depending upon the desired characteristics of the outputhigh pressure flow, the pump system 10 can include any of a variety ofcam 50 to pressuring subassembly 60 relations.

In operation, the drive mechanism 20 induces rotation of the cam 50. Therotating cam 50, by contact of the cam profile 56 and the cam follower74 of each pressurizing subassembly 60, controls the velocity of eachpiston rod 90. The velocity of the piston rod 90 relative to thehigh-pressure cylinder 110 (and in conjunction with a downstreamdischarge orifice and the upstream and downstream check valves) providesa corresponding increase in fluid pressure. The velocity of the pistonrod 90 relative to the high-pressure cylinder 110 can be a function of aconstant rotation rate of the cam 50, or a varied cam rotation * rate incombination with a predetermined cam profile 56 so as to provide aconstant output pressure and flow rate.

Although the present pump system 10 can be used to provide a variety ofpressures and flow rates, it is anticipated the flow rate will be lessthan 20 gallons per minute at a pressure greater than 30,000 psi, anddepending upon the sealing configuration, greater than 100,000 psi. Itis also understood that the pump system 10 can characterized as a highpressure pump providing pressures greater than approximately 10,000 psi.

It is also contemplated, the pump system 10 can be configured to providea substantially constant high-pressure flow rate at selectedintermittent intervals. By substantially constant, it is understood thatthe flow rate is within 10% of a given value. The intermittent constanthigh-pressure output flow rate can be provided by selectively ventingthe pump system 10, or controlling the drive mechanism 20. For example,the high-pressure flow path downstream of the pump system 10 can includea dump valve, such as a pressure relief valve or a bypass valve to passthe high-pressure flow to a drainage system or an on/off valve.Alternatively, the drive mechanism 20 can be controlled to temporarilycease creating high pressure output.

The interchangability of the cam 50 in the pump system 10 allows a givensystem to provide different output flow rates and pressures in responseto use of corresponding cams. That is, a given pump system 10 with afirst cam could provide 2 gallons per minute (gpm) at 30,000 psi and 1gpm at 50,000 psi with a different second cam. Thus, the pump system 10can be configured to provide output pressures from 10,000 psi (oftendefined as a minimum threshold for high pressure) to 100,000 psi with anoutput flow rate from 0.25 gpm to 20 gpm.

Thus, by merely designing the cam profile 56, a given pump system can beconfigured to provide a variety of output flow rates and pressures.

The constant output high-pressure pump system 10 can thus be used forwaterjet cutting, cleaning, surface preparation and sterilization.

While the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives,modifications, and variations will be apparent to those skilled in theart in light of the foregoing description. Accordingly, the presentinvention is intended to embrace all such alternatives, modifications,and variations as fall within the spirit and broad scope of the appendedclaims.

1. A high pressure open discharge pump system, comprising: (a) a baseplate; (b) a cam shaft rotatably mounted to the base plate; (c) a camaffixed to the cam shaft for rotation with the cam shaft; (d) at least afirst and a second pressurizing subassembly in contact with the cam,each pressurizing subassembly including: i. a piston guide blockconnected to the base plate; ii. a piston rod slidably connected to thepiston guide block; iii. a cam follower support connected to the pistonrod; iv. a linear guide bearing connecting the cam follower support tothe base plate; v. a cam follower connected to the cam follower supportto contact the cam; vi. a high pressure cylinder assembly releasablyconnected to the guide block to receive a length of the piston rod, thehigh pressure cylinder assembly including at least one sealed interfacebetween the piston rod and the high pressure cylinder assembly; (e) atie brace connected to each piston guide block.
 2. The high pressureopen discharge pump system of claim 1, wherein the tie brace isrotatably connected to the cam shaft.
 3. The high pressure opendischarge pump system of claim 1, wherein the tie brace connects eachguide block to the base plate.
 4. The high pressure open discharge pumpsystem of claim 1, further comprising a downstream head and a checkvalve external to the high-pressure cylinder assembly, the check valvebeing fluidly intermediate the head and the high-pressure cylinderassembly.
 5. The high pressure open discharge pump system of claim 1,wherein the high-pressure cylinder assembly includes a high-pressurecylinder, the sealed interface between the high-pressure cylinderassembly and the piston rod being formed between the high-pressurecylinder and the piston rod.
 6. The high pressure open discharge pumpsystem of claim 1, further comprising a check valve in at least onepressurizing subassembly.
 7. The high pressure open discharge pumpsystem of claim 1, further comprising a second cam affixed to the camshaft.
 8. The high pressure open discharge pump system of claim 1,further comprising a return bias mechanism connected to at least onepressurizing subassembly to maintain contact between the cam and the camfollower throughout rotation of the cam.
 9. The high pressure opendischarge pump system of claim 1, wherein the cam follower support is ayoke.
 10. The high pressure open discharge pump system of claim 1,wherein the first pressurizing subassembly and the second pressurizingsubassembly are equally spaced about the cam shaft.
 11. Thehigh-pressure open discharge pump system of claim 1, wherein the firstpressurizing subassembly and the second pressurizing subassembly arespaced unequally about the cam shaft.
 12. The high-pressure opendischarge pump system of claim 1, further comprising a first valvingbody in the first pressurizing subassembly and a second valving body inthe second pressurizing subassembly.
 13. The high-pressure opendischarge pump system of claim 1, wherein the tie brace is fixedrelative to the base plate.
 14. The high-pressure open discharge pumpsystem of claim 1, wherein the tie brace is releasably fastened to thebase plate.
 15. The high-pressure open discharge pump system of claim 1,further comprising a check valve fluidly connected to the high-pressurecylinder assembly in the first pressurizing subassembly upstream of thepump system.
 16. The high-pressure open discharge pump system of claim1, further comprising a check valve fluidly connected to thehigh-pressure cylinder assembly in the first pressurizing subassemblydownstream of the pump system.
 17. The high-pressure open discharge pumpsystem of claim 1, wherein the base plate includes at least one subplate.
 18. The high-pressure open discharge pump system of claim 1,wherein the base plate is an integral structure.
 19. The high-pressureopen discharge pump system of claim 1, wherein the base plate is a onepiece construction.
 20. A high-pressure cylinder assembly releaseablyengaging a piston guide block and cooperatively receiving areciprocating piston rod connected to a drive mechanism, thehigh-pressure cylinder assembly comprising: (a) a pair of spaced endplates, one of the end plates including an aperture sized to slidablyreceive the reciprocating piston rod; (b) a high pressure cylinderdisposed between the end plates, the high pressure cylinder defining acylinder chamber sized to receive a portion of the reciprocating pistonrod; (c) a valving body partially disposed between the end plates, thevalving body including at least one passageway fluidly communicatingwith the cylinder chamber; (d) a first stationary seal forming aninterface with the reciprocating piston rod; (e) a second stationaryseal between the valving body and the high pressure cylinder; and (f)releasable engaging means for releasably engaging one of the end platesto the piston guide block
 21. The cylinder assembly of claim 20, furthercomprising a check valve fluidly connected the valving body.
 22. Thehigh-pressure cylinder assembly of claim 20, further comprising meansfor releasably retaining the end plates in a predetermined spacing. 23.The high-pressure cylinder assembly of claim 20, further comprisingmeans for applying a clamping force between the end plates.
 24. Thehigh-pressure cylinder assembly of claim 20, further comprisingreleasable engaging means for releasably engaging the piston rod to acam follower support.
 25. A high-pressure cylinder assembly releasablyengaging a piston guide block and cooperatively receiving areciprocating piston rod connected to a drive mechanism, thehigh-pressure cylinder assembly comprising separable high pressurecylinder, at least one end plate and a seal between the high pressurecylinder and the piston rod.
 26. A method for providing a high-pressuredischarge in an open end system, the method comprising: (a) contactingat least a first cam follower and a second cam follower with a rotatingcam, the first cam follower connected to a first cam follower supportand the second cam follower connected to a second cam follower support,the first cam follower support connected to a base plate by a firstlinear guide bearing and the second cam follower support connected tothe base plate be a second linear guide bearing; (b) connecting a firsthigh pressure cylinder to a first guide block; (c) connecting a secondhigh pressure cylinder to a second guide block; (d) connecting a firstpiston rod to the first cam follower support to provide a reciprocatingmotion of the first piston rod through the first guide block and withinthe first high pressure cylinder; (e) connecting a second piston rod tothe second cam follower support to provide a reciprocating motion of thesecond piston rod through the second guide block and within the secondhigh pressure cylinder; and (f) connecting a first tie brace to thefirst guide block; and (g) connecting the first tie brace to one of thecam shaft and the base plate.
 27. The method of claim 26, furthercomprising connecting the first tie brace to one of the cam shaft, thesecond guide block and the base plate.
 28. The method of claim 26,further comprising releasably connecting the first high-pressurecylinder to the first guide block.
 29. The method of claim 26, furthercomprising releasably connecting the second high-pressure cylinder tothe second guide block.
 30. The method of claim 26, further comprisingconnecting a piston ring to one of the first and the second piston rods.31. The method of claim 26, further comprising releasably connecting thefirst piston rod to the first cam follower support.
 32. The method ofclaim 26, further comprising releasably connecting the second piston rodto the second cam follower support.
 33. The method of claim 26, furthercomprising equally spacing the first cam follower and the second camfollower about the cam.
 34. The method of claim 26, further comprisingunequally spacing the first cam follower and the second cam followerabout the cam.